Pediatrics

WHO Criteria for Severe Malaria

Any ONE of the following in the presence of P. falciparum (or, less commonly, severe P. vivax) parasitemia: impaired consciousness/cerebral malaria, prostration, multiple seizures, respiratory distress/acidotic breathing, circulatory collapse/shock, pulmonary edema/ARDS, abnormal bleeding/DIC, jaundice with other severity signs, severe anemia (Hb <5 g/dL in high-transmission settings), hypoglycemia, acute kidney injury, and hyperparasitemia.

Pathophysiology of Cerebral Malaria

Results from sequestration of parasitized RBCs in cerebral microvasculature, mediated by parasite surface adhesion molecules (notably PfEMP1) binding host endothelial receptors — causing microvascular obstruction, impaired perfusion, and cytokine-mediated cerebral edema/encephalopathy. This sequestration is a distinguishing feature of P. falciparum specifically.

Parenteral Artesunate Protocol

IV (or IM, if IV access not feasible) Artesunate is the treatment of choice across all ages (AQUAMAT trial — significant mortality reduction vs IV quinine). Dosing: initial dose at 0 hr, then at 12 hr and 24 hr, then once daily, continued until oral tolerance, followed by a full oral course of an ACT (Artemisinin-based Combination Therapy) to complete treatment.

Radical Cure Guidelines

For confirmed/suspected P. vivax (dormant liver hypnozoites causing relapse risk), radical cure requires a hypnozoite-active agent: Primaquine (14-day course) or Tafenoquine (newer single-dose alternative, improved adherence). Both carry risk of severe hemolysis in G6PD-deficient individuals — mandatory G6PD screening before administration is non-negotiable; if unavailable, use cautious weekly primaquine dosing or withhold radical cure pending testing.

Clinical Course and Complications

Enteric fever (predominantly Salmonella Typhi; Paratyphi A/B causing milder illness) follows a progressive weekly pattern if untreated. Feared complications: intestinal perforation (terminal ileum, ~3rd week, surgical emergency) and typhoid encephalopathy (the "typhoid state" — altered, confused mental status from severe systemic toxemia), occurring predominantly with delayed/inadequate treatment.

Blood Culture vs Serology

Blood culture is the gold standard, sensitivity highest in week 1, declining thereafter — should be obtained before antibiotics. The Widal test is widely used in resource-limited settings but has poor sensitivity/specificity, cross-reactivity, and endemic-population titer confounding; a four-fold titer rise between paired samples provides more reliable, though retrospective, support.

Management of Drug-Resistant Salmonella Typhi

Emergence of XDR Salmonella Typhi — resistant to ampicillin, chloramphenicol, co-trimoxazole, widespread fluoroquinolone resistance across South Asia, and growing resistance to third-generation cephalosporins and azithromycin (notably in parts of Pakistan) — represents an evolving challenge.

• Ceftriaxone: mainstay first-line empirical choice for moderate-severe disease (regionally variable susceptibility)
• Azithromycin: effective oral option for uncomplicated disease, retains activity against many fluoroquinolone-resistant isolates
• Meropenem: important escalation option for confirmed ceftriaxone-/azithromycin-resistant isolates

Categorization of Animal Bites (WHO Exposure Categories)

Wound Care

Immediate, thorough washing with soap and water for a minimum of 15 minutes is the single most important, immediately actionable measure, performed before further formal evaluation or vaccine/RIG administration.

Rabies Immunoglobulin (RIG) Administration

RIG provides immediate passive protection bridging the ~7–14 day gap before active immunity develops. Critically, RIG must be infiltrated directly into and around the wound, with any remaining volume given IM at a site distant from the vaccine injection site. Both Human RIG (HRIG) and Equine RIG (ERIG) are available; ERIG requires prior skin testing.

Vaccination Schedules — Intradermal vs Intramuscular

• IM (Essen) regimen: 5 full IM doses on days 0, 3, 7, 14, 28 (deltoid, or anterolateral thigh in young children)
• ID regimen: dose-sparing, cost-saving, comparable immunogenicity — Updated Thai Red Cross (TRC) regimen: 2 sites on days 0, 3, 7, 28; increasingly adopted in national PEP programs including India

Pathogenesis of Acute Flaccid Paralysis (AFP)

Poliovirus (fecal-oral transmission) causes paralysis via selective destruction of anterior horn motor neurons (and, in bulbar polio, brainstem motor nuclei), producing asymmetric, flaccid paralysis with preserved sensation — distinguishing it from Guillain-Barré syndrome (symmetric, sensory involvement).

VAPP vs VDPV — A Critical, Frequently-Confused Distinction

Global Polio Eradication Endgame Strategy

• tOPV → bOPV switch (April 2016): global withdrawal of the type 2 OPV component after wild poliovirus type 2 was certified eradicated; type 2 Sabin strain was disproportionately responsible for VDPV events.
• Fractional IPV (fIPV): dose-sparing intradermal strategy, comparable immunogenicity to full-dose IM IPV at lower cost; incorporated into India's UIP for type 2 protection.
• nOPV2: genetically more stable alternative for outbreak response to cVDPV2 events without the same reversion risk.

Clinical Manifestations — Congenital Syphilis

Early congenital syphilis (within first 2 years, typically first few months): hepatosplenomegaly, maculopapular/vesiculobullous rash (including palms and soles), snuffles (blood-tinged nasal discharge), lymphadenopathy, jaundice, osteochondritis/periostitis ("Parrot's pseudoparalysis").

Late congenital syphilis (after age 2): the classic Hutchinson's triad — Hutchinson's teeth (notched, peg-shaped upper central incisors), interstitial keratitis, sensorineural deafness — plus saber shins, saddle nose deformity, frontal bossing.

Serological Tests

For congenital syphilis diagnosis, an infant titer four-fold or greater than the maternal titer supports true congenital infection (though a lower titer does not fully exclude it).

Lumbar Puncture Indications

CSF examination (CSF-VDRL, cell count, protein) is generally recommended for all infants evaluated for possible congenital syphilis, particularly those with clinical signs, inadequately treated maternal infection, or a diagnostic-threshold titer.

Penicillin Treatment Regimens

• Congenital syphilis: Aqueous Crystalline Penicillin G IV for 10 days (reliable CNS penetration)
• Acquired syphilis (early stages): Benzathine Penicillin G, single IM dose (inadequate CSF penetration — not for neurosyphilis/congenital disease with CNS involvement)

Etiological Spectrum of AES in India

• Japanese Encephalitis (JE): mosquito-borne flavivirus, historically the single most significant identified AES cause in endemic states (UP, Bihar, Assam, etc.); target of national vaccination program (UIP endemic districts).
• Chandipura virus: India-specific (central India) rhabdovirus, fulminant illness predominantly in young children, very high case-fatality rate.
• Nipah virus: paramyxovirus from fruit bat reservoirs, severe often-fatal encephalitis with notable person-to-person/nosocomial transmission potential.
• Herpes Simplex Virus (HSV): smaller proportion numerically but disproportionate clinical importance as the ONE etiology with specific, highly effective treatment (aciclovir).
• A substantial proportion of AES cases remain of unidentified etiology despite thorough investigation.

Diagnostic Approach

CSF examination (lymphocytic pleocytosis, mildly elevated protein, generally preserved glucose), specific PCR (HSV, JE, enteroviruses per suspicion), serology (IgM, particularly valuable for JE), and neuroimaging (MRI preferred) — HSV classically shows asymmetric temporal/limbic involvement; JE classically shows a thalamic-predominant pattern.

Empiric Management

Given the time-critical, treatable nature of HSV encephalitis, empirical IV Aciclovir should be initiated promptly in any child with a clinical picture suggestive of encephalitis, without waiting for PCR confirmation, and continued unless/until HSV is confidently excluded. Management for non-HSV causes is predominantly supportive: seizure management, ICP monitoring, fluid/electrolyte management (SIADH risk), general critical care — no specific antiviral exists for JE, Chandipura, or Nipah, underscoring the importance of preventive strategies.

Clinical Spectrum

Abrupt-onset fever, myalgia, headache, cough, sore throat, ranging from mild illness through severe complications: primary viral pneumonia, secondary bacterial pneumonia (classically S. aureus and S. pneumoniae superinfection), myocarditis, encephalopathy; in young infants, presentation can mimic bacterial sepsis (fever without localizing signs).

High-Risk Groups

Children <2 years, those with chronic pulmonary disease (including asthma), cardiac disease, immunocompromise, chronic neurological/neuromuscular conditions, metabolic disorders (diabetes), and significant obesity — warrant prioritized vaccination and lower threshold for antiviral treatment.

Diagnostic Testing

RT-PCR is preferred (most sensitive/specific, allows typing/subtyping). Rapid antigen tests are faster but meaningfully less sensitive — a negative result does not reliably exclude influenza, particularly in high-risk/severely ill children.

Antiviral Therapy

Oseltamivir is most effective when initiated within 48 hours of symptom onset — the central timing principle. However, treatment should still be considered beyond 48 hours in children who are severely ill, hospitalized, or in high-risk groups, given continued evidence of benefit (including mortality benefit in hospitalized patients) even with delayed initiation.

Pathophysiology of Secretory Diarrhea

Rotavirus damages mature absorptive villous enterocytes, causing reduced absorption and, critically, active secretion mediated by the viral enterotoxin NSP4, which stimulates intestinal chloride secretion — producing profuse watery diarrhea with significant dehydration risk.

Dehydration Assessment

WHO/IMNCI-aligned assessment based on general appearance/mental status, eye appearance, thirst/ability to drink, and skin pinch/turgor — categorized as no dehydration, some dehydration, or severe dehydration, each with a specific management pathway.

WHO ORS Composition (Low-Osmolarity Formula)

Zinc Supplementation

10 mg/day for infants <6 months, 20 mg/day for children ≥6 months, given for a 10–14 day course — reduces diarrhea duration/severity and risk of subsequent episodes over 2–3 months.

Rotavirus Vaccines and Intussusception Risk

Oral live-attenuated rotavirus vaccines carry a small but real, well-documented increased intussusception risk, concentrated in the first 1–7 days after the first dose (first identified with the withdrawn RotaShield vaccine). The overwhelming consensus is that the benefit of preventing severe rotavirus disease/mortality substantially outweighs this small absolute risk — the vaccine series is initiated within specific age windows to minimize administration during the period of highest baseline intussusception incidence.

Clinical Stages

Incubation (10–14 days) → Prodromal phase (2–4 days: high fever, the "3 C's" — cough, coryza, conjunctivitis — and pathognomonic Koplik spots on buccal mucosa) → Exanthem phase (maculopapular rash with cephalocaudal spread, fever peaking around rash onset) → Convalescence (rash fades in the same cephalocaudal sequence).

Atypical Measles

Historical presentation in recipients of the older, inactivated (killed) vaccine, with reversed (peripheral-to-central) rash spread and higher pneumonia/complication incidence — now predominantly of examination interest.

Complications

Acute: otitis media, pneumonia (viral and secondary bacterial), diarrhea. Giant cell (Hecht's) pneumonia: distinctive severe form in immunocompromised children. Subacute Sclerosing Panencephalitis (SSPE): rare, uniformly fatal, progressive neurodegenerative disease from persistent defective measles CNS infection, typically manifesting 7–10 years after primary infection; younger age at primary infection (<2 years) is a risk factor. No effective treatment — prevention via vaccination is the only strategy.

Vitamin A Administration

Recommended for all children diagnosed with measles regardless of nutritional status, given robust mortality/morbidity reduction evidence. Standard dosing: two doses on consecutive days, with a third dose 2–4 weeks later for children with ocular signs of vitamin A deficiency.

Measles-Rubella (MR) Elimination Campaign Goals

Incorporated into India's UIP (two-dose schedule at 9–12 and 16–24 months) with periodic supplementary immunization activities, addressing both measles morbidity/mortality burden and rubella's Congenital Rubella Syndrome risk (cardiac defects, cataracts, sensorineural deafness from first-trimester maternal infection).

Pathophysiology

EBV (a gamma-herpesvirus) infects B lymphocytes; the clinical syndrome reflects a robust cytotoxic T-lymphocyte response against infected B cells, rather than direct viral cytopathic effect.

Clinical Triad

Fever, pharyngitis (often exudative, can mimic strep pharyngitis — amoxicillin/ampicillin given for a mistaken bacterial diagnosis classically triggers a florid maculopapular rash), and lymphadenopathy (characteristically including posterior cervical nodes). Splenomegaly is common and clinically significant given rupture risk.

Laboratory Findings

Atypical lymphocytes on peripheral smear. The heterophile antibody test (Monospot) is rapid but has reduced sensitivity in children <4 years — a negative test in a young child should not be considered reassuring; EBV-specific serology (VCA IgM/IgG) is more reliable in this age group.

Complications

• Splenic rupture: rare but serious — avoid contact sports/abdominal trauma for 3–4 weeks or until splenomegaly resolves.
• Hemophagocytic Lymphohistiocytosis (HLH): EBV is a well-recognized infectious trigger; consider with unexpectedly severe, prolonged, or atypical course with evolving cytopenias.